Does Butter Get Moldy? (What Mold On Butter Looks Like & How To Prevent It!)

It’s a question that has been debated for years – does butter get moldy?

Butter is a dairy product, and as with all dairy products, it can develop mold. The likelihood of moldy butter depends on the butter type and how it is stored.

Butter is made up of butterfat, milk proteins, and water. The ratio of these ingredients will ultimately determine how long the butter will last.

Butter higher in butterfat, like European-style butter, will have a longer shelf life than those with a lower butterfat percentage.

In this blog post, we will take a closer look at what butter is and how it’s made, why it’s susceptible to mold, and good habits you can adopt to extend the shelf life of your butter.

How does the type of butter affect the shelf life?

Before we can discuss the moldy components of butter, it’s helpful to understand what butter is and how it’s made.

Butter is a dairy product produced by churning cream that has been separated from milk. There are many different types of butter; their classifications vary based on the fattiness of the butter.

Butter is basically just fat that has been separated from milk, hence the name “buttermilk.”

It’s typically made by churning the separated cream into the semi-solid state we know as butter. This happens because the fat membranes stick together as they are agitated.

If you’re interested in learning more, here’s an easy overview of the many different types of butter these days:

Type of butterDescription
Unsalted butterMost versatile, contains at least 80% milkfat
Salted butterGreat for spreading on bread, not used as commonly as unsalted butter, good shelf-life
Clarified butter (Ghee)Pure fat resulting from straining milk solids out of the butter, great shelf-life
Organic butterCan be found unsalted or salted, made from cows raised without antibiotics or growth hormones
Whipped butterLighter in texture, good for spreading but not typically used in cooking
European-style butterHigh in milkfats (82-85%), less moisture than regular butter produces great shelf-life

Does butter get moldy?

Butter is known for its long shelf life and versatility between cooking and baking. Can butter get moldy?

Yes, butter can get moldy. As a result of butter being a dairy product, it is susceptible to mold growth. If you find mold on your butter, you should throw it away to avoid resulting respiratory issues.

Mold loves damp and warm environments, and if the temperatures in your home are too high, the butter will melt and become a breeding ground for mold spores. If you store your butter in the fridge, keep it in a sealed container.

If you’re unsure if your butter is still good, smell it before using it. If it smells off, don’t use it.

Seeing as butter is a natural staple in many kitchens, you must know how to store it properly. Moldy butter is not safe to eat, so throw it away if you see mold on it.

loaf of bread with butter

Why does butter grow mold?

Butter is a dairy product made from the fatty parts of the milk. It’s high in fat and contains a lot of moisture, making it the perfect environment for mold to grow.

How does this relate to moldy butter?

As a result of the butter-making process, butter is susceptible to mold. Its moisture provides a breeding ground for mold, and the fatty acids that comprise butter are perfect for mold to feed and latch onto.

If you leave the butter out on the counter, it will grow mold within a few days, called “spoilage.” It may not be visible during the early stages of mold growth, although there are indicators we will cover later in this article.

The mold will continue to grow as long as the butter is left out, eventually turning the butter green or black. Visible mold is a dead giveaway that you should definitely throw your butter out, starting with a fresh stick for your next recipe.

moldy butter with red x that needs to be thrown away

How do you keep butter from molding? (5 tips to prevent moldy butter)

Now that you understand why butter gets moldy, how can you maximize the lifespan of your butter by preventing mold from growing?

Unfortunately, you can’t stop mold from growing; butter is a dairy product, and like all dairy products, it will eventually spoil and develop mold. However, you can do a few things to extend its shelf life.

While you can’t entirely prevent your butter from getting moldy, we do have 5 tips to ensure you use up all your butter before mold starts growing:

  1. Keep your butter in the refrigerator – by keeping butter in a cold environment such as a fridge, the butter takes longer to oxidize. This, in turn, deters mold growth. Bonus tip: store it at the back of the fridge rather than the door.
  2. Don’t leave your butter out for extended periods of time – this is an extension of keeping your butter in a cool environment. Leaving it out for too long speeds up the oxidation process.
  3. Make sure the butter is well-wrapped – keep the butter wrapped up tightly to seal it off from oxygen and other flavors or odors. When storing it in the fridge, it’s best kept in its original wrapping; some folks will recommend using foil, but this actually speeds up oxidation.
  4. Avoid cross-contaminating your butter – using a butter knife that has been used on other food products is a big no-no. The knife could be potentially contaminated from previous products, spurring mold growth. Make sure to clean the knife in between uses.
  5. Consider buying salted butter – salt is a natural preservative that will increase the lifespan of your butter. If you’re concerned about the added salt in regards to taste or dietary restrictions, reference this guide about how to adjust your salt measurements when using salted butter.

What does mold on butter look like? (4 signs your butter is bad)

If you’re unsure about how to determine if your butter is growing mold, there are multiple tell-tale signs.

A funky color, slimy or softened texture, sour smell, or rancid taste indicates your butter is moldy. If any of these characteristics apply to your butter, discard it in the trash immediately.

Luckily, even if it isn’t visible, it’s easy to tell if your butter is moldy!


Mold on butter can take on many different appearances, depending on the type of mold present.

Moldy butter can be white, black, green, or even pink.

It can also appear as a fuzzy growth or as slimy patches.

The reasoning behind the differing appearance of mold is that mold reacts differently to different levels of light and humidity. Every scenario is unique, and therefore mold isn’t exactly uniform in appearance.


If the color of your butter seems right, your next check should be on the texture.

Moldy butter will also have a different texture than fresh butter. Typically, it will be hard and crumbly in comparison to good butter.

It will be softer and may even have a slightly different color, as we mentioned above. For example, if the mold is white, the butter may appear yellowish.


You should give the butter the smell test if you’re unsure about its state.

Moldy butter will have a musty or sour smell. It is similar to other dairy products, such as milk or cheese.

Butter gets really smelly due to the chemical breakdown that occurs when mold feeds on butter.

Well, how long does it take butter to reach this smell? It can range from 1 to 3 months as long as you store your butter in the fridge.

If you store it at room temperature, it will likely develop a rancid smell much quicker.

gif dog smelling something and fainting


While you probably don’t want to know what moldy butter tastes like, you’ll realize it the second it hits your tastebuds.

Moldy butter will taste sour and unpleasant, not unlike drinking sour milk.

If you eat moldy butter, you may experience nausea or vomiting. In technicality, this is known as “food objection” rather than food poisoning.

If you eat butter with Penicillium mold, you may experience diarrhea. If you eat butter with Aspergillosis mold, you may experience headaches, fever, and respiratory problems.

I’ll be clear, though: food-induced nausea sucks either way. Don’t eat moldy butter!

What happens if you eat moldy butter?

If you’ve ever found a tub of butter in your fridge covered in mold, you may have wondered if it’s still safe to eat.

In fact, I’ve heard of people cutting the mold off your butter and eating it. Good as new, right?


The short answer is that it’s not going to kill you, but it could make you sick. Mold can cause gastrointestinal issues like nausea and vomiting and allergic reactions in some people. Additionally, eating moldy butter could trigger a dangerous anaphylactic reaction if you’re allergic to mold.

If you find mold on your butter, it’s best to throw it out and buy a new tub or stick.

Eating a little mold isn’t likely to cause severe harm, but why take the risk? Regarding food, it’s always better to err on the side of caution.

Should butter be refrigerated?

Many families keep their butter on the kitchen counter in a butterbell. Is this permissible, or should they refrigerate their butter?

While you don’t need to refrigerate your butter, it will last much longer if you do. Storing your butter at room temperature will keep it for about two weeks compared to 1 to 3 months if you keep it in the fridge.

So, what’s the practical takeaway? If you plan to use all your butter within two weeks, storing it in the kitchen is alright. Be sure to store it in a cool, dry place that is not in direct sunlight.

However, if you can, you should still try to keep it refrigerated. It’s a lot easier to take the safe route and know that the food you’re eating is safe.

butter stored in the fridge with other cold perishable items

How do you know if butter has gone bad?

You might be surprised to learn that butter can go wrong. If you’ve ever found a tub of butter in your fridge covered in mold, you know this to be true. But how do you know if the butter has gone bad?

There are a few telltale signs that your butter has gone bad.

First, look at the color to see if it’s anything other than a creamy white. Any departure from butter’s natural color isn’t a good sign!

Second, give it a smell. If it smells sour or rancid, it’s time to get rid of it.

Third, you can try the taste test. Take a small bite of the butter to see if it tastes off. If it does, spit it out and throw the rest of the butter away.

Fourth, check the texture. If the butter is hard or crumbly, it’s probably past its expiration date.

Finally, take a look at the packaging. If the butter is packaged in foil or plastic, it should have a “use-by” date. If that date has passed, the butter is no longer safe to eat.

If you’re unsure whether your butter has gone bad, the best thing to do is throw it out. I don’t know about you, but I certainly have no desire to throw up my dinner because of some questionable butter!

Is it OK to cut mold off butter?

No, it is not advisable to cut mold off of butter. It is still possible the butter is contaminated even if the visible mold has been removed; miniscule spores may still exist.

How long does it take for butter to go Moldy?

When stored at room temperature, butter can grow mold as quickly as two weeks. When stored in the fridge, butter can last as long as 3 months. In the freezer, it can last an entire year.

What is the white stuff on butter?

There are multiple possibilities. It could be mold, salt, or even separated milkfats. If you suspect it might be mold, it’s best to just toss it out and use new butter.

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